Main » Infectious diseases » Arthropod-borne Infection » Yellow Fever
Yellow fever occurs today in South America and tropical Africa. It is mosquito transmitted. Vaccination provides a high level of protection for 10 years and is a legal requirement for travellers entering endemic countries. The main differential characters of the common types of mosquito vectors of disease are shown in the next figures
Distribution map of yellow fever virus
Culex (1) eggs are deposited on the water surface in 'rafts'(x 25). Aedes (2) eggs are laid singly. They often have a conspicuously sculptured surface. (x25) Anopheles (3) eggs have lateral floats. They tend to aggregate on the water surface forming 'Chinese figure' patterns.
Photo 1. Mosquito eggs (Culex).
Photo 2. Mosquito eggs (Aedes).
Photo 3. Mosquito eggs (Anopheles).
The larvae of Culex (4) and Aedes (5) are suspended under the air water interface by their siphons. Those of Anopheles (6) lie parallel to the surface.
Photo 4. Mosquito larvae(Culex).
Photo 5. Mosquito larvae (Aedes).
Photo 6. Mosquito larvae (Anopheles).
Pupae of culicines (8) and Anopheles (9) are very similar. They obtain air through siphons on the cephalothorax.
Photo 7. Mosquito pupae (culicines).
Photo 8. Mosquito pupae (Anopheles).
Adult famale Culex
Photo 9. Adult female Culex hatching from pupa — Mature pupa.
Photo 10. Adult female Culex hatching from pupa — moment of hatching.
Photo 11. Adult female Culex hatching from pupa — emerged female.
Adults of the different families and general are recognised by the form of the antennae and palps.
Photo 12. Heads of adulf culicine and anopheline mosquitoes (Culex).
Photo 13. Heads of adulf culicine and anopheline mosquitoes (Aedes).
Photo 14. Heads of adulf culicine and anopheline mosquitoes (Anopheles).
Photo 15. Aedes vector biting.
Photograph taken at midday in rain forest near Belem at the mouth of the River Amazon. Mosquitoes of the genera Aedes (Stegomyia) and Haemagogus transmit tfye virus from forest monkeys, which form a sylvatic reservoir for yellow fever virus, to man, and subsequently from man to man.
Photo 16. Water containers near houses — vector breeding sites. Aedes aegypti breeds in domestic water containers and is responsible for urban epidemics.
Photo 17. "Black vomit" of yellow fever. Despite the name, jaundice is usually not marked in yellow fever. Bleeding from the gut is a grave portent, and vomiting of material resembling coffee grounds such as that shown gere occurs.
Photo 18. Section of liver from fatal yellow fever case.
Photo 19. Electron micrograph of yellow fever virus.
Photo 20. Temperature chart of yellow fever case. The increasing slowness of the pulse relative to the temperature (Faget's sign) is of clinical diagnostic value. D refers to day of illness, P refers to pulse and T to temperature °C.
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